Java连接Zookeeper操作指南

连接Zookeeper并对其进行基本操作，是Java开发人员的常见需求。本文将详细介绍如何实现这一目标。

一、配置依赖

在开始操作之前，需要确保项目中已正确导入Zookeeper相关的依赖。以下是一个示例的Maven POM文件：


     
    
     4.0.0
      
    
     cn.zookeeper
      
    
     zookeeper_demo
      
    
     0.0.1-SNAPSHOT
      
        
           
      
       org.apache.zookeeper
            
      
       zookeeper
            
      
       3.4.6

二、编写工具类与测试代码

接下来，我们来看如何编写用于连接Zookeeper并执行基本操作的工具类代码。

package zookeeper_demo;import java.util.List;import java.util.concurrent.CountDownLatch;import org.apache.zookeeper.CreateMode;import org.apache.zookeeper.KeeperException;import org.apache.zookeeper.WatchedEvent;import org.apache.zookeeper.Watcher;import org.apache.zookeeper.Watcher.Event.KeeperState;import org.apache.zookeeper.ZooDefs.Ids;import org.apache.zookeeper.ZooKeeper;import org.apache.zookeeper.data.Stat;public class BaseZookeeper implements Watcher {    private ZooKeeper zookeeper;    private static final int SESSION_TIMEOUT = 2000;    private CountDownLatch countDownLatch = new CountDownLatch(1);    @Override    public void process(WatchedEvent event) {        if (event.getState() == KeeperState.SyncConnected) {            System.out.println("接收到连接状态通知");            countDownLatch.countDown();        }    }    public void connectZookeeper(String host) throws Exception {        zookeeper = new ZooKeeper(host, SESSION_TIMEOUT, this);        countDownLatch.await();        System.out.println("Zookeeper连接成功");    }    public String createNode(String path, String data) throws Exception {        return zookeeper.create(path, data.getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);    }    public List
   
     getChildren(String path) throws KeeperException, InterruptedException {        return zookeeper.getChildren(path, false);    }    public String getData(String path) throws KeeperException, InterruptedException {        byte[] data = zookeeper.getData(path, false, null);        return (data != null) ? new String(data) : "";    }    public Stat setData(String path, String data) throws KeeperException, InterruptedException {        return zookeeper.setData(path, data.getBytes(), -1);    }    public void deleteNode(String path) throws InterruptedException, KeeperException {        zookeeper.delete(path, -1);    }    public String getCTime(String path) throws KeeperException, InterruptedException {        Stat stat = zookeeper.exists(path, false);        return String.valueOf(stat.getCtime());    }    public Integer getChildrenNum(String path) throws KeeperException, InterruptedException {        return zookeeper.getChildren(path, false).size();    }    public void closeConnection() throws InterruptedException {        if (zookeeper != null) {            zookeeper.close();        }    }    public static void main(String[] args) throws Exception {        BaseZookeeper zookeeper = new BaseZookeeper();        zookeeper.connectZookeeper("192.168.126.128:2181");        List
    
      children = zookeeper.getChildren("/");        System.out.println("根节点的子节点数量：" + children.size());    }}

三、实现说明

上述代码包含以下主要功能：

连接Zookeeper：通过connectZookeeper方法建立与Zookeeper服务器的连接。

节点操作：

创建节点：使用createNode方法，支持指定路径和数据内容。

获取子节点：getChildren方法用于获取指定路径下的所有子节点。

获取节点数据：getData方法可以读取指定路径下的节点数据。

设置节点数据：setData方法用于更新节点的数据内容。

删除节点：deleteNode方法用于删除指定路径的节点。

获取节点创建时间：getCTime方法返回指定路径节点的创建时间。

获取子节点数量：getChildrenNum方法返回指定路径下的子节点数量。

四、使用示例

以下是使用上述工具类代码的示例：

// 初始化Zookeeper实例BaseZookeeper zookeeper = new BaseZookeeper();// 连接Zookeeper服务器zookeeper.connectZookeeper("localhost:2181");// 创建一个持久化节点String path = "/my-node";String data = "这是一个测试节点";System.out.println("创建节点结果：" + zookeeper.createNode(path, data));// 获取根节点下的子节点List
   
     children = zookeeper.getChildren("/");System.out.println("根节点的子节点：" + children);// 获取某个节点的数据System.out.println("节点数据：" + zookeeper.getData(path));// 删除节点zookeeper.deleteNode(path);System.out.println("节点已被删除");